Finishing devices are also known as “shortstroke honing devices” and are described, e.g., in DE 10 2007 059 926 A1 (corresponding to US 2009/0142997 A1) and 44 23 422 A1.
Such devices are used for the finish machining of circumferential surfaces of substantially rotationally symmetrical workpiece portions on workpieces, such as crankshafts or camshafts. Finishing is a precision machining method, in which the circumferential surfaces of substantially rotationally symmetrical workpiece portions on workpieces (such as main journals and pin journals of a crankshaft) are worked for producing a particularly smooth surface structure. Finishing involves a machining tool having a granular cutting compound of a finishing stone or belt being pressed by a pressing device onto the circumferential surface to be worked. To produce the cutting speed necessary for material removal, in many method variants the workpiece is rotated about its workpiece axis and simultaneously an oscillating relative movement parallel to the workpiece axis is produced between the workpiece and the machining tool engaging on the circumferential surface. As a result of the combination of the rotary movement of the workpiece and the superimposed oscillatory movement a so-called crosscut pattern can be produced, so that the worked workpiece circumferential surfaces are particularly suitable e.g. as contact surfaces for roller or plain bearings, etc.
The workpieces can e.g. be camshafts or crankshafts. Such workpieces are provided in axially spaced manner with mutually rotationally symmetrical workpiece portions serving as bearing points. The so-called main bearings or journals are positioned coaxially to the workpiece axis and serve to mount the shaft for its rotary movement within the engine housing. Immediately alongside a main journal are provided one or two so-called pin, stroke or lift journals, whose axes are parallel and displaced eccentrically to the workpiece axis. Other parts of a machine, e.g. the connecting rods of pistons of an internal combustion engine or a pump or a compressor engage on the pin journals.
During the finish machining of such workpieces, use is generally made of devices making it possible to simultaneously work or machine several of the workpiece portions of the same workpiece. Such finishing devices have a number of finishing units, each of the finishing units having at least one finishing tool and wherein each of the workpiece portions to be machined is associated to one of the finishing units.
When used for large-scale production, for example when finishing the crankshaft of a four-cylinder engine commonly used in a great number of vehicles, setting up a finishing device may consume a considerable amount of time and effort which then is compensated for by an extended operation time of the device. Such a compensation is difficult or impossible to achieve when using the finishing method for medium and small batch production, thus making this method comparatively expensive.
The present invention discloses a finishing device which is particularly well suited for a medium or small batch production.